The present invention relates to a radiant glossing apparatus for glossing developer sheets and a process for using the same.
The developer sheet useful in the present invention can be used in conjunction with conventional pressure-sensitive copy paper or photosensitive imaging systems employing microcapsules to provide visible images upon contact with a color precursor which is image-wise released from the microcapsules and transferred to the developer sheet.
Photosensitive imaging systems employing microencapsulated radiation-sensitive compositions are the subject of commonly assigned U.S. Pat. Nos. 4,399,209 and 4,416,966 as well as copending U.S. patent application Ser. No. 320,643 filed Jan. 18, 1982. These imaging systems are characterized in that an imaging sheet including a layer of microcapsules containing a photosensitive composition in the internal phase is image-wise exposed to actinic radiation. In the most typical embodiments, the photosensitive composition is a photopolymerizable composition including a polyethylenically unsaturated compound and a photoinitiator and is encapsulated with a color precursor. Exposure image-wise hardens the internal phase of the microcapsules.
U.S. Pat. No. 4,399,209 discloses a transfer system in which the imaging sheet is assembled with a developer sheet prior to being subjected to the rupturing force. Upon passing through pressure rollers in contact with the developer sheet, the microcapsules rupture and image-wise release the internal phase whereupon the color precursor migrates to the developer sheet where it reacts with a dry developer and forms a color image. Imaging systems can be designed to produce monochromatic or polychromatic full color images.
In most processes for glossing a developer sheet, heat or a combination of heat and pressure is used to gloss the thermoplastic developer resin. See commonly assigned U.S. Pat. No. 4,554,235. As examples of heat glossing, the developer sheet can be glossed by heating the sheet in contact with a heated roller or a pair of heated rollers. The developer sheet can also be passed over a heated platen or alternatively, the developer sheet can be placed in a hot oven.
Radiant heating sources disposed within reflectors are known for applying heat to a substrate. For example, U.S. Pat. No. 4,021,641 teaches the use of a source of radiant energy within a reflector plus a lens structure for focusing energy onto toner images. The lens is in the form of a belt positioned around the energy source and the reflector. The belt is disposed entirely above the substrate having the toner images such that the energy is focused through the belt onto the toner images.
Known processes for glossing developer sheets suffer from numerous disadvantages. In glossing processes wherein the developer sheet surface having a thermoplastic developer resin thereon contacts a belt which urges the sheet over a heated surface, resin build-up on the belt over a long period of time can occur. In processes involving a belt which transports a substrate beneath a heating element, the belt can act as a heat sink with respect to the heat applied by the heating element. Thus, a need exists in the art for a glossing apparatus for glossing developer sheets and a process for using the same wherein no resin build-up occurs and the transporting means does not act as a heat sink.